1. Field of the Invention
The present invention relates generally to liquid crystal display devices and, more particularly, to color liquid crystal display devices of the active matrix type.
2. Description of Related Art
Active-matrix liquid crystal display devices are typically designed to define, as pixel regions, regions which are surrounded by a plurality of parallel-provided gate signal transmission lines and a plurality of parallel drain signal transfer lines crossing these gate signal lines on the liquid crystal side surface of one substrate of respective substrates that are disposed to oppose each other with a layer of liquid crystal material interposed therebetween.
Each pixel region is equipped with a switching element which is activated by a scanning signal from a gate signal line and a pixel electrode to which an image signal is supplied from a drain signal line through this switching element.
In addition, in such liquid crystal display devices, when letting them perform color display operations, a color filter is formed at each pixel on the liquid crystal side surface of, for example, the other substrate of the above-noted respective substrates, wherein this color filter is arranged to use filters exhibiting red (R), green (G) and blue (B) for respective ones of three pixels which neighbor upon one another.
An arrangement called the delta layout is known, wherein a group of pixels along a gate signal line are disposed in such a manner as to let each pixel of an even-numbered linear array or line, for example, be shifted or offset by ½ pixel distance with respect to each pixel of an odd-numbered line while at the same time letting three color-display pixels consisting of two mutually neighboring pixels of an even-numbered line and a single pixel of an odd-numbered line which is in close proximity thereto and also two neighboring pixels of the odd-numbered line and a single pixel of the even-numbered line adjacent thereto, which disposed alternately.
A liquid crystal display device with such delta layout is capable of improving the display quality by disposing respective three color-display pixels at respective top points or apexes of a triangle and also blurring the contour thereof. However, since the liquid crystal display device arranged in this way is arranged to shift the pixel group of an even-numbered line by ½ pixel distance with respect to the pixel group of an odd-numbered line in the way described above, a drain signal line which runs between respective pixels must be formed to have several perpendicularly bent or curved portions. This structure has been actualized as inconvenient points occurring due to the quest for higher definition of liquid crystal display devices in the recent years. That is wire breakage or an “open-circuit” is easier to generate at the aforementioned curved portions which is accompanied with a decrease in line width of the drain signal lines. It is considerd that this is caused by an increase in etching rate at the curved portions of the drain signal lines when compared to that at the other portions in cases where the drain signal lines are fabricated and patterned through selective etching by photolithography techniques, for example.